This application claims the benefit of Japanese Application Nos. Hei. 11-199289, filed in Japan, on Jul. 13, 1999, Hei. 11-222856, filed in Japan, on Aug. 5, 1999, Hei. 11-224524, filed in Japan, on Aug. 6, 1999, 2000-172344, filed in Japan, on Jun. 8, 2000, the contents of which are incorporated herein.
1. Field of the Invention
The present invention relates to an endoscope which is characterized in the structure of contents disposed in a space within the endoscope and which accommodates to autoclave sterilization.
2. Related Art Statement
An endoscope which allows an operator to observe deep inside of a body cavity by inserting an insert section thereof and to carry out remedial operations by using operation tools as necessary has come to be widely used lately.
In case of a medical endoscope, it is essential to sterilize and disinfect the endoscope following use to prevent infectious diseases and the like. Hitherto, surgeons have achieved this disinfecting and sterilization process with sterilization gas, such as ethylene oxide gas (EOG) and on disinfectant solutions.
However, as it has been known widely, it has been cumbersome to carry out disinfecting and sterilization by sterilization gas. There has been also a problem that the tool cannot be used right away after such sterilization because it takes time for aeration to remove the gas adhered to the tool after sterilization. Still more, it has been a problem that its running cost is high.
Use of a disinfectant solution has had drawbacks in that it is cumbersome to control the solution and that it takes much cost for disposal of such solution.
Autoclave sterilization, or high-pressure steam sterilization, which requires no cumbersome works and allows the tools to be used right away after sterilization and has a running cost that is low is now becoming the mainstream of endoscope disinfecting and sterilization processes.
The typical conditions of the autoclave sterilization are described in the US Standard ANSI/AAMI ST37-1992 authorized by the American Standards Association and published by the Medical Equipment Development Association and published by the Medical Equipment Development Association. According to the conditions, the sterilization step had to be carried out at 132xc2x0 C. for four minutes in a pre-vacuum type or at 132xc2x0 C. for ten minutes in a gravity type.
The autoclave sterilization is actually carried out by infiltrating steam in a range of about 120xc2x0 C. to 140xc2x0 C. about a subject to be sterilized under high pressure of about 0.2 Mpa.
However, the high-temperature and high-pressure steam of autoclave sterilization has the ability of penetrating through polymer materials, such as rubber and plastics and adhesives, which are used for composing the endoscope. Accordingly, when the conventional endoscope, which is constructed to be water-tight endoscope with O-ring and adhesives, is sterilized by autoclave steam infiltrates through the water-tight endoscope.
When the steam infiltrates the endoscope by autoclave sterilization, the steam penetrates through the adhesives of the lens system and infiltrates the lens system. Therefore, there is a possibility that water drops remain on the lens surface or the lens and the adhesive for joining the lenses deteriorates, thus blocking the field of view.
Epoxy resin, which is adhesive, generally used for a long time, deteriorates when exposed to high-temperature steam. Therefore, it is possible that the steam is liable to infiltrate the lens systems as the adhesive peels off.
It also is possible that the adhesive peels off due to stress which occurs between parts due to differences of coefficients of thermal expansion of the materials composing the respective parts, thus the steam infiltrates the lens system because the temperature of autoclave sterilization is high.
A circuit board and electronic parts mounted on the circuit board, a joint part of the circuit board and lead wires and a joint part of the lead wires and connectors composing an image pickup device, for example, stored in he endoscope are coated and protected by epoxy adhesive or silicon adhesives. However, because the epoxy and silicon adhesives have high hygroscopic properties, there is a possibility that the circuit board and the electronic parts mounted on the circuit board, the joint part of the circuit board and the lead wires and the joint part of the lead wires and the connectors corrode by the high-temperature and high-pressure steam when the steam which has infiltrated the endoscope reaches those parts.
In view of these circumstance, hermetically closing the inside of the lens system by means of soldering has been used instead of jointing by the adhesives.
For instance, Laid-Open Japanese Patent Application No. Hei. 10-234649 has disclosed a hard scope which prevents cloudiness and deterioration of the lenses and deterioration of the adhesives by forming a hermetic package by hermetically assembling a cover glass at the front end of an inner cylindrical tube and by hermetically assembling a hermetic connector which can electrically connect the inside and the outside, while maintaining airtightness, to a rear end of the inner cylindrical tube and by inserting and assembling an objective lens system within the hermetic package. According to this arrangement, the objective lens group is fixed to a frame which holds the objective lens group in focus with respect to a solid image pickup device. The whole objective optical system composed of the focused objective lens group, the objective lens group holding frame and the solid image pickup device is inserted to the inner cylinder. It is noted that airtightness means tightness to a degree sustainable to the high-temperature and high-pressure steam of autoclave sterilization in the present application.
However, the hard scope in Laid-Open Japanese Patent Application No. Hei. 10-234649 has had a drawback in that the outside shape of the insert section is large because the hermetic package is provided within the insert section.
That is, although the arrangement described above may be adopted for the hard scope, which permits the hermetic package of the objective optical system to be long, it is hardly adoptable for a scope having a bend in which the hermetic package of the objective optical system must be stored at the front end beyond the bend section. When this arrangement is adopted for an endoscope having a bend, it causes a trouble in that the hard lengthy part at the front end beyond the bend section becomes long, thus increasing a burden on patients.
It is noted that steam infiltrating an endoscope during autoclave sterilization adheres to an angle wire in the endoscope in which wires formed by stranded wires by bundling metallic element wires, such as conventional stainless wires, is used as the angle wire for controlling the bend section of the endoscope. This creates a possibility that the angle wire rusts as the steam remains in the gap between the element wires.
The angle wire has been coated variously to increase slippage thereof for a long time. However, the coating has not been carried out steadily in the gap between the element wires and in the part not contacting with other parts, so that it could not prevent rust across the whole wire.
Further, de-flick coat, which is coating containing molybdenum disulfide, which has been used as a coating material in general for a long time, is not only unable to coat the gap between the element wires, but also is deteriorated and peeled off by the high-temperature and high-pressure steam of autoclave sterilization. Therefore, the de-flick coat did not function as a rust preventive coating at all.
Accordingly, it is an object of the invention to provide an endoscope which is susceptible to autoclave sterilization and which allows an optical unit disposing section to be formed small and to be disposed at the front-end portion of an endoscope having a bend.
Another object of the invention is to provide an endoscope which is susceptible to autoclave sterilization and which allows an optical unit to be assembled favorably.
A further object of the invention is to provide an endoscope which is susceptible to autoclave sterilization and which has an optical unit constructed at low cost.
Yet another object of the invention is to provide an endoscope which experiences no failure of the bend due to problems with an angle wire, even if autoclave sterilization is carried out.
Briefly, the inventive endoscope which can endure high-temperature and high-pressure steam comprises an optical unit having at least one optical member; an optical unit supporting frame for supporting the optical unit so that the position thereof can be adjusted in the direction of an optical axis; and a hermetic optical covering member which is joined to the optical unit supporting frame and has an optical window covering at least the end portion of the optical unit when it is joined.